Polyurethane Interpenetrating Polymer Networks (IPN's) Synthesized under High Pressure. 1. Morphology and Tg Behavior of Polyurethane-Poly(methyl methacrylate) IPN's

Abstract

A series of simultaneous interpenetrating polymer networks of polyurethane-poly(methyl methacrylate) were synthesized under high pressure (up to 20,000kg/cm2). The morphology via transmission electron microscopy and the glass transition behavior via DMA and DSC measurements were studied, and the effect of the synthesis pressure was evaluated. The composition of the polyurethane and poly(methyl methacrylate) was fixed at 50/50% by weight. The polyurethane phase domain sized decreased from about 300 to 30 À with increasing synthesis pressure from 1250 to 20,000kg/cm2. The phase continuity changed also with pressure; the polyurethane phase became continuous at low pressure, while the poly(methyl methacrylate) phase showed continuity at high pressure. A very broad glass transition ranging from about 0 to about 100 °C was observed for IPN’s synthesized under 20,000kg/cm2, and they were optically transparent.